Suspension systems are used, for example, in utility machines such as tractors or the like. In order to provide the driver with a highest possible comfort, utility machines can additionally be outfitted with a cab suspension in addition to the conventional vehicle suspensions.
In traditional systems, a costly control technology is often necessary to ensure a damping of the suspension system that is as smooth as possible. For the most part an expensive sensor system that registers the hydraulic status of the relevant hydraulic cylinder is required.
EP 2 197 697 B1 describes a suspension system, in particular a cab suspension, which has a hydraulic cylinder connected to a hydraulic reservoir. The system includes a throttle valve with two throttles. When the hydraulic cylinder is retracted, the entire fluid flow that is forced out of the piston chamber first flows through the first throttle and is then divided into a partial flow that flows into the hydraulic reservoir, and a partial flow that flows into the rod chamber of the hydraulic cylinder.
During extension, all of the fluid flow forced out of the rod chamber flows through the second throttle to the piston chamber of the hydraulic cylinder, and fluid is additionally supplied to the piston chamber from the hydraulic reservoir.
The two throttles have open cross sections that correspond to the ratio of the piston surface to the ring-shaped area of the hydraulic cylinder. Through this, the movement is damped the same in the case of extension and retraction if the valve setting is the same, since the fluid flows either through the one or the other throttle opening depending on the direction of movement.
This construction with two throttles is costly and necessitates a high expense for dimensioning the throttles causing power losses, since it can also lead, for example, to heating of the hydraulic fluid. In addition, the components become highly stressed during operation.